This is the 5744th most frequent Russian word.
продолжали
"Продолжали" means "continued" in English.
Here, 'продолжали' is used to indicate the continuation of an activity in which the subjects were already engaged, namely 'our conversation'.
Мы продолжали наш разговор до поздней ночи.
We continued our conversation until late at night.
In this case, 'продолжали' reflects the ongoing action of walking, which the subjects didn't cease performing even under challenging circumstances.
Они продолжали идти по тропинке, несмотря на туман.
They continued walking along the trail despite the fog.
The usage of 'продолжали' shows the perseverance in conducting research, highlighting sustained effort over a period of time.